The present invention relates to medical instruments utilized in aspirating liquid samples from bone structures.
A biopsy medical instrument is an instrument which is designed to take samples of tissue. Typically, a biopsy device that is utilized to obtain samples from the bone consists of a hollow cannula that is surrounding a stylet. The stylet includes a sharp distal tip which extends outwardly from the cannula when the stylet is secured inside the cannula. The combined cannula and stylet is used to penetrate through the outer layer of the bone, called the cortex, which is considerably harder than the trabecular bone layer and the tissue within the bone that is sampled, referred to as the marrow. Once the stylet and cannula have penetrated the cortex, the stylet is removed and the cannula is extended further into the medular cavity, thereby capturing marrow tissue for a sample.
The architecture of the tissue sample that is removed by the biopsy device is critical in several respects. Initially, the size of the sample is important, with larger tissue sample sizes representing better samples for subsequent testing to be performed on the tissue. However, the larger the cannula and stylet that are inserted into the bone, the more pain is generated at the site of the penetration for the patient. In addition, it is important that the sample be taken without damaging the marrow tissue. However, in removing the tissue sample the tissue must be excised from the remaining tissue. This removal can result in compromising the tissue sample by damaging the tissue sample.
Several approaches have been taken to secure large, undamaged tissue samples using bone marrow biopsy devices. However, each of these approaches has significant drawbacks which limit commercial and clinical usefulness. For example, one such approach utilizes suction provided at the proximal end of the cannula. The suction is designed to pull the tissue sample into the cannula and retain the tissue sample inside the cannula. While in theory such suction would help secure larger tissue samples, in practice exposure to such suction forces results in damage to the marrow tissue when the sample is removed from the patient.
Another approach utilizes a snare in the form of a coil at the distal end of the cannula. When rotated, the coil decreases in diameter to secure the biopsy tissue sample in the cannula. While again in theory such a device would help secure larger tissue samples, in practice it subjects the tissue sample to compression forces which causes damage to the sample.
Other approaches include the use of inwardly projecting members such as scallops within the cannula. The theory behind such devices is that when the tissue sample is captured by the cannula, the inward direction of the scallops allows the tissue sample to slide over such projecting members but when the tissue sample is removed from the patient the projecting members latch onto the tissue sample to secure the tissue sample in the cannula. Again, however, this theory fails in practice as it causes trauma to the tissue when the tissue sample is removed from the patient.
Other approaches include providing apertures on the side of the cannula which, in theory, allow tissue to expand into such apertures to help secure the tissue sample in the cannula. Likewise, one approach utilizes a screw member in the cannula which is designed to urge the tissue inwardly and retain the tissue sample in of the cannula. Once again, providing a cavity for the tissue sample that is not smooth results in damage to the tissue when the tissue sample is removed from the patient.
Yet another approach at securing the biopsy sample within the cannula involves the use of a pair of coaxial cannulas. One of the two cannulas includes a curved section that acts as a cam to compress the inner cannula around the tissue sample when the inner cannula is withdrawn from the outer cannula. Once again, in theory this would help to secure the tissue within the cannula, but in practice it subjects the tissue sample to such compression forces that damage to the sample is caused. In addition, the use of dual cannulas acts to either decrease the size of the tissue sample or to increase the size of the biopsy device causing increased pain to the patient. A similar approach utilizes an additional coaxial hollow cannula designed to sheer or cut-off the tissue when the two cannulas are rotated relative to each other. However, because such devices require additional hardware in the cannula, either the size of the tissue sample is decreased or the size of the biopsy device is increased.
In addition, it is often clinically useful to aspirate the bone marrow to obtain marrow liquid for additional testing. With devices of the prior art, an outer cannula and a stylet of a biopsy needle is used to gain access to the medular cavity through the cortex of the bone. The stylet is removed and suction is applied in order to pull the marrow liquid out of the marrow tissue.
Because of the trauma such aspiration causes to the marrow tissue due to thrombotic cascading, considerable destruction to the marrow tissue occurs at the site of the aspiration. Thus, in the prior art a tissue sample taken through the same access site as the aspiration would be adulterated. Therefor, a tissue sample is typically taken from an access site separate from the aspiration site. Two separate access sites result in increased pain to the patient and increased possibility of infection.
What would be desirable is an aspiration device that is able to aspirate a sample while minimizing the pain experienced by the patient during such procedure. Such a device would also avoid subjecting the patient to an increased risk of infection.
The present invention provides an aspiration device that is able to aspirate a sample while minimizing the pain experienced by the patient during such procedure. The present invention further avoids subjecting the patient to an increased risk of infection. The present invention provides an aspiration device that includes an outer cannula, a stylet and a hollow cannula with an aperture. The outer cannula defines a distal tip that is tapered to provide a distal cutting edge. The stylet is designed to be inserted in the outer cannula. The stylet also defines a sharp distal tip. The hollow cannula is designed to be inserted in the outer cannula. The distal end of the hollow cannula is closed and an aperture is defined in a side of the hollow cannula.
Thus, there is disclosed an aspiration device comprising: an outer cannula secured in a handle, the outer cannula defining a distal tip that provides a distal cutting edge; a stylet designed to be inserted in the outer cannula, the stylet defining a sharp distal tip; a hollow cannula designed to be inserted in the outer cannula; and an aperture defined in a side of the hollow cannula.
Thus, there is further disclosed an aspiration device comprising: a housing; a hollow cannula secured in the housing, a distal end of the hollow cannula being closed; and an aperture defined in a side of the hollow cannula.
There is further disclosed an aspiration device comprising: an outer cannula secured in a handle; a stylet designed to be inserted in the outer cannula; and a hollow cannula designed to be inserted in the outer cannula, the hollow cannula adapted to define an aspiration zone generally to the side of the hollow cannula.
There is disclosed a kit for administering an aspiration comprising: an outer cannula secured in a handle, the outer cannula defining a distal tip that provides a distal cutting edge; a stylet designed to be inserted in the outer cannula, the stylet defining a sharp distal tip; a hollow cannula designed to be inserted in the outer cannula; and an aperture defined in a side of the hollow cannula.
There is disclosed a method for aspirating bone marrow tissue comprising: inserting a stylet into an outer cannula; penetrating the bone cortex with the stylet and the outer cannula to enter the medular cavity; removing the stylet; inserting an aspiration needle into the outer cannula; creating a suction through the aspiration needle; removing the aspiration needle; further inserting the outer cannula into the medular cavity, thereby trapping bone marrow tissue within the outer cannula; and removing the bone marrow tissue from the patient.